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A160420 Number of "ON" cells at n-th stage in simple 2-dimensional cellular automaton whose skeleton is the same network as the toothpick structure of A139250 but with toothpicks of length 4. 10
0, 5, 13, 27, 41, 57, 85, 123, 149, 165, 193, 233, 277, 337, 429, 527, 577, 593, 621, 661, 705, 765, 857, 957, 1025, 1085, 1181, 1305, 1453, 1665, 1945, 2187, 2285, 2301, 2329, 2369, 2413, 2473, 2565, 2665, 2733, 2793, 2889, 3013, 3161, 3373, 3653, 3897, 4013 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) is also the number of grid points that are covered after n-th stage by an polyedge as the toothpick structure of A139250, but with toothpicks of length 4.

LINKS

Table of n, a(n) for n=0..48.

David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

FORMULA

Conjecture: a(n) = A147614(n)+2*A139250(n). [From R. J. Mathar, Jan 22 2010]

The above conjecture is true: each toothpick covers exactly two more grid points than the corresponding toothpick in A147614.

EXAMPLE

a(2)=13:

.o-o-o-o-o

.....|....

.....o....

.....|....

.....o....

.....|....

.....o....

.....|....

.o-o-o-o-o

CROSSREFS

Cf. A139250, A139251, A147614, A147562, A160118, A160120, A160170, A160430.

Sequence in context: A180671 A211637 A256111 * A182840 A147411 A008580

Adjacent sequences:  A160417 A160418 A160419 * A160421 A160422 A160423

KEYWORD

nonn

AUTHOR

Omar E. Pol, May 13 2009, May 18 2009

EXTENSIONS

Definition revised by N. J. A. Sloane, Jan 02 2010.

Formula verified and more terms from Nathaniel Johnston, Nov 13 2010

STATUS

approved

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Last modified February 24 18:24 EST 2018. Contains 299628 sequences. (Running on oeis4.)